IBI3033

This is a Phase 1, randomized, double-blind, placebo-controlled, multiple ascending dose study designed to evaluate the safety, tolerability, and pharmacokinetics of IBI3033 in subjects with moderate-to-severe atopic dermatitis (AD). Approximately 16 eligible adult participants will be enrolled and sequentially assigned to one of two dose cohorts. Within each cohort, participants will be randomized in a 3:1 ratio to receive IBI3033 or matching placebo. The study consists of a screening period (up to 4 weeks), a 12-week treatment period, and a 4-week safety follow-up period. The primary objective is to assess safety and tolerability based on the incidence of adverse events and serious adverse events. Secondary objectives include characterization of pharmacokinetics and immunogenicity. Exploratory assessments include pharmacodynamic biomarkers and preliminary efficacy outcomes such as changes in Eczema Area and Severity Index (EASI) and Investigator's Global Assessment (vIGA-AD) scores.